********************************** More ASTER data of Merapi Volcano ********************************** From: Michael Ramsey <mramsey+@xxxxxxxx> The ASTER sensor has continued to image and monitor the ongoing volcanic eruption at Merapi, Indonesia, albeit at a lower temporal frequency than the previous six weeks. A clear nighttime thermal infrared (TIR) and shortwave infrared (SWIR) set of images were acquired on 22 June and a overview of the results are presented below. Three images have been processed into PDF files and posted at the same location as past data sets: http://ivis.eps.pitt.edu/data/merapi/ In contrast to past ASTER data, this image shows the dominant thermal anomaly now being directed to the SE away from the summit and extending 6.4 km downslope (presumabley cooling PFD's). The most distant 90m pixel shows a 1.3 C thermal elevation above the background and is only detectable because ASTER's high radiometric and spatial resolution in the TIR region. The advance of the SE flow continues the past trend of this direction slowly becoming the dominant flow path and the SW direction becoming less so (compare to data collected on 30 May 2006). Temperatures at the summit continue to be near or at the saturation limit for ASTER TIR and SWIR. Only one ASTER TIR pixel was saturated at the summit (T greater than 100 C over the 90 square meter area). This pixel is colored dark red in the image. At the 30m/pixel SWIR spatial resolution, 2 pixels showed temps in excess of 425 C. This is the same spatial and thermal extent as reported in the 6 June 2006 data. It appears that the dome has not changed much in terms of thermal output over the past 2 weeks. In a preliminary analysis of the plume, SO2 still appears to be at or below the detection limit for the ASTER TIR bands. A decorrelation stretch image has been posted and shows a much more extensive and diffuse plume (over 18 km away from the summit to the NW) as compared to the 6 June image. In this color combination, water/ice clouds tend to be indicated by the blue to cyan colors, ash is indicated by red colors, and SO2 would be indicated by yellow to orange. The plume is dominated by blue to magenta colors indicating a mix of ash and water vapor/ice with low amounts of SO2. More analysis will continue on these and past ASTER data. I will continue to post new information as data becomes available. Cheers, Mike +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Dr. Michael Ramsey, Associate Professor Dept. of Geology & Planetary Science, University of Pittsburgh 4107 O'Hara Street, room 200 SRCC Pittsburgh, PA 15260-3332, USA office: 412-624-8772; fax: 412-624-3914; IVIS Lab: 412-624-8773, IVIS Spectrometer Lab: 412-624-7874 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ ============================================================== To unsubscribe from the volcano list, send the message: signoff volcano to: listserv@xxxxxxx, or write to: volcano-request@xxxxxxxx To contribute to the volcano list, send your message to: volcano@xxxxxxxx Please do not send attachments. ==============================================================
